Field of the Invention
The invention relates to a method and to a device for laminating a profiled fibre moulding with a thermoplastic film, wherein the film is laminated onto the surface of the fibre moulding to be coated by means of heat and differential pressure.
Description of Related Art
Generally, joining processes have long been the usual state of the art. Thus, U.S. Pat. No. 2,796,634 shows, by way of example, a moulding and joining process for mouldings made from two relatively solid layers. In these processes, the external surface is to remain as undamaged as possible and thus provide an intact face side of, for example, household appliances and furniture. For this purpose, the outer layer is initially thermally heated and mechanically pre-formed by means of one rigid and one movable mould half, thus bringing it closer to the later shape. The two layers are subsequently connected and the moulding brought into its final shape.
In addition, it has long been known to coat even profiled fibre mouldings with difficult geometries with a thermoplastic film by laminating fibre moulding and film to each other. A gas- or fluid-tight coating is desirable by way of example if the fibre mouldings are to be used as packaging elements for containers for liquids such as drinks or food.
It is known from U.S. Pat. No. 3,657,044 to coat a profiled fibre moulding with a thin thermoplastic film by incorporating the film under the effect of heat and vacuum into the fibre moulding and laminating it thereto. This method has proven itself with respect to the older spraying or dipping methods. The film is fixed between two mould components in the process in order to be immovably fixed at its outer edge. The construction effort for this known laminating method is considerable and a uniform thickness of the laminated film can only be achieved with simple geometries.
Further thermoforming methods for laminating profiled fibre mouldings with a thermoplastic film are known separately from DE 25 47 477 A1 and DE 25 47 814 A1.
DE 25 47 477 A1 describes a device and a method for conducting air into the thermoforming station of thermoplastic films. It deals in particular with the conduction of air and different temperatures during lamination. To avoid cooling of the heated film by the impinged vacuum it is proposed to vault the heated film by means of a stamp in the direction of the surface of the fibre moulding to be coated.
DE 25 47 814 A1 describes a machine for lining paper cups with a plastics material film that is to be thermoformed into the cup. Closed moulds are no longer used here and instead the individual film sections are mechanically fixed to a circumferential frame. Both of the documents mentioned above disclose a pure thermoforming method for final deformation of the plastics material film used, however.